Remove fixed item.

diff --git a/TODO b/TODO
index 5bf19c1d3c94176bbc9e523b0538e12b893fa4ce..95bf2aeb4ff2994762d6440765fb3e85d03eb2f9 100644 (file)
--- a/TODO
+++ b/TODO
@@ -109,29 +109,6 @@ Subject: 3 questions about switch_threads() in switch.S
 To: blp@cs.stanford.edu, joshwise@stanford.edu
 Date: Fri, 3 Mar 2006 17:09:21 -0800
 
-QUESTION 1
- 
-In the section
- 
-  # Save current stack pointer to old thread's stack, if any.
-  movl SWITCH_CUR(%esp), %eax
-  test %eax, %eax
-  jz 1f
-  movl %esp, (%eax,%edx,1)
-1:
-
-  # Restore stack pointer from new thread's stack.
-  movl SWITCH_NEXT(%esp), %ecx
-  movl (%ecx,%edx,1), %esp
-
-why are we saving the current stack pointer only if the "cur" thread pointer
-is non-NULL ? Isn't it gauranteed to be non-NULL because switch_threads() is
-only called form schedule(), where we have
-
-  struct thread *cur = running_thread ();
-
-which should always be non-NULL (given the way kernel pool is laid out).
-
 QUESTION 2
 
   # This stack frame must match the one set up by thread_create().